In proposal we will investigate the role of epigenetic mechanisms in the pathogenesis of allergic asthma and rhinitis. Asthma affects 1 in 15 Americans - over 23 million people - thus making it one of the country's most common and also costly diseases. Current therapies do not cure asthma or control daily symptoms for patients with severe disease, prompting us to adopt out-of-box approaches to find novel therapies for asthma. Our goal is to directly address the unmet need for asthma sufferers by harnessing the seminal discoveries made in the field of epigenetics to benefit asthma research. Multiple lines of evidence suggest an important role for epigenetic mechanisms in asthma. Specifically, we have identified disease-specific epigenetic signatures in the T helper 2 (TH2) cytokine locus (encompassing the 1L4, IL5 and ILI 3 genes) in patients with moderate asthma compared to patients with mild asthma or controls. In addition, we recently discovered TET proteins that convert 5-methylcytosine (5mC) to 5-hydroxymethyl-cytosine (hmC)in DNA, thus creating a completely new epigenetic mark; and have shown that Tet proteins and 5hmC are expressed in T cells. These are exciting findings because hydroxylation of 5mC alters DNA methylation status in a hitherto unprecedented way, and because DNA methylation is relevant to several fields including mammalian development, cancer, aging, cell lineage specification, genome defense, stem cell function and immunology. We propose to extend these studies to identify epigenetic signatures that correlate with asthma development and severity, by comparing histone modifications and DNA methylation/ hydroxy-methylation patterns in enriched populations of pathogenic epitope-specific T cells isolated from blood of allergic rhinitis subjects and asthmatic patients, categorized based on clinical severity into mild and moderately severe asthmafics. Our study will be the first to define disease-related epigenetic changes in patients with wellcharacterized asthma, and to correlate these with disease severity to obtain specific markers for disfinguishable disease states.